Fabric resination



United States Patent This invention relates to an improvement in the process for imparting durable finish effects to natural cellulose fabric by impregnating the fabric with resinous materials and thereafter fixing the resin in the fabric. The invention also relates to the novel fabric produced by the improved process. 4 v

The invention is particularly concerned with processes for the enhancement of certain properties-notably the wet resilience or wash and wear properties of the fabric. The improved process involves certain special operational techniques which are to be used as pretreatments in conjunction with conventional resinating processes and which permit enhancement of the influence of the resin on the fabric properties.

These special techniques produce the beneficial effects entirely independent of resination and are described in my copending application Serial No. 804,857, filed April 17, 1959.

However, when the special techniques described in application Serial No. 804,857 are used to pretreat fabric which is to be subjected to resination, certain benefits are obtained in addition to those secured when the techniques are employed without resination. In particular, the-pretreatment enables the resinto more efficiently exert its influence on the fabric properties.

For example, a given degree of stabilization can be obtained with less resin when the fabrics have been given the special preparatory treatment than can be obtained if the pretreatment has not been employed; or, stated in another way, the pretreatment will enhance the resination effects produced by a given quantity of resin.

The special pretreatment conditions the fabric and makes it more receptive to the resin. This is accomplished by modifying the celluloseespecially the crystal lite phase and thereby enables obtaining a more uniform dispersion of the resin in the cellulose complex. The modification tends to affect the crystallite phase and impart to it some of the characteristics of the amorphous phases. As a result of this treatment, it is possible for the relatively large resin particles to penetrate into and exert their influence on areas which, in the absence of the pretreatment, they could not effectively reach.

As the process of resination is well known and understood by those skilled in the art, I shall not describe in great detail the many possible variations thereof. The pretreatment steps will be found to impart beneficial properties to natural cellulose fabrics which are to be subjected to any presently known type of fabric resination;

' Essentially the resination process involves the steps of applying a resinous material to the fabric, usually in the form of an aqueous solution of a water soluble heathardenable resin precondensate, drying the fabric, and then heating the fabric in the presence of a curing catalyst to fix the resin in the fabric.

As used herein, the term resinous material is intended to mean not only the thermosetting type impregnants but also those impregnants which react with the cellulose or other impregnants to form a water insoluble complex.

As is also well known, between impregnation and curing the fabric can, if desired, be subjected to mechanical treatments which tend to change the form and relative disposition of the fabric fibers, e.g. calendering, pleating, compressive shrinking, and the like; and if the fabric is cured while maintained in the deformed condition, the

' wet to dry condition and to dry fiat.

ice

However, where white goods such as shirtings, are to be 'resinated (either with or without mechanical treatments), the preferred type of resinous material is one which is not discolored by halogen (e.g. the chlorine frequently used in bleaches). Many of the textile finishing resins will,to some extent, pick-up and retain chlorine in commercial laundering operation s. Therefore, it is also preferred to employ resins which either do not pickup chlorine, or if theydo pick-up chlorine, which will not readily release the chlorine during subsequent ironing, in quantities or at rates which will objectionably degrade the cellulose. Examples of especially suitable resins for treating white goods, include the cyclic ureasespecially triaZone precondensates; ketone aldehydes, and the like. It is also customary to tintwhite goods. Where tinting agents are to be applied in the process of. the present invention, it is preferred that they be applied to the goods intermediate the decrystallization and resination operation.

Turningnow to a detailed consideration of the special techniques to be employed in conjunction with the various resination treatments, the pretreatments are of such a nature that beneficial results are obtained only in the processing of natural cellulose. Regenerated celluloses and esterified celluloses cannot be effectively treated by these special techniques.

As described in my copending application Serial No.

' 804,857 the pretreatment techniques which are especially useful in conjunction with resination processes utilize certain physico-chemical and chemical techniques (either singly or in combination) which permit a portion of the dense, highly oriented cellulose crystallites to be modified opened up or spread apart (hereinafter this phenomenon will sometimes be referred to as decrystallization) so as to impart to the crystallite some of the characteristics of the disoriented amorphous phase-particularly the ability to recover from a deformed state on passing from the The techniques which enable the desired type and degree of crystallite modification or decrystallization to be obtained involve either swelling the fabric under certain prescribed conditions or reacting fabric with certain.

reagents which tend to open up and/ or modify the crystallite or by combinations of the two techniques in any desired sequence.

In general, these special techniques are treatments which affect the cellulose crystallites and bring about physical and/or chemical modification of the crystallite phase in a way that enhances the wet resilience of the fabric without exerting any commercially significant adverse influence on the strength, sewability and other characteristics. The special treatment techniques also tend to enhance certain other fabric characteristics such as the hand, dye and resin receptivity, drapability, etc.

According to one aspect of my invention, 1 have discovered that it is possible to enhance certain properties, particularly the resin receptivity and the wet resilience of the fabric, by methylenating the fabric with agents which can penetrate the cellulose crystallites as well as the amorphous phases, and carrying out the methylenation under conditions which control the degree of methylenation within certain readily reproducible limits and which at the same time predictably minimize degradation of the cellulose. I

According to another aspect of my invention, I have discovered that it is possible to enhance certain prop erties, particularly the resin receptivity and the wet resilience of the fabric, by swelling the fabric in strong Patented June 30, 1964 it should first be noted that tion, it is preferred to have them in the bleached un.

mercerized state for if the fabric has been previously mercerized, the mercerization treatment will have caused deconvolution or untwisting of the fibers and thereby tend to exert an adverse influence on the hand and strength of the fabric treated according to the herein disclosed processing techniques. Prepared fabrics which have been scoured, dewaxed and bleached, appear to give more uniform results.

We will first consider the special methylenation control techniques of the present invention which are intended to modify the crystallite phase and insure the distribution of methylene crosslinking groups substantially uniformly throughout the cellulose (i.e. in both crystallite and in the amorphous phases) and thereafter we will discuss the techniques to be employed in effecting decrystallization by physico-chernical methods.

CHEMICAL DECRYSTALLIZATION For satisfactory results an average of at least one methylene crosslink should be introduced for every 10 to 200 glucose residues (i.e. equivalent to reacting a quantity of formaldehyde equal to about 2 to 0.1% of the fabric weight and giving an add on of from 0.8 to 0.4% of the fabric weight) in the cellulose complex. If the average number of crosslinks formed is less than 1 to 200 the crystallite phase Will not be affected sufiiciently to significantly enhance the wash and wear or fiat drying properties. Whereas, if the average number of crosslinks is greater than 1 to 10 the fabric will be tendered appreciably and it will not have the strength necessary to undergo machine laundering and drying. For most purposes I have found that an average of l methylene crosslink for every 30 to 100 glucose residues (i.e. equivalent to reacting a quantity of formaldehyde equal to 0.2 to 0.6% of the weight of the fabric and giving an add on of from 0.08% to 0.24%) gives the optimum results in that wet resilience will be appreciably enhanced and strength losses will be held well within acceptable commercial tolerances.

As used herein the term methylene crosslink is intended to refer to crosslinks of the type:

wherein R represents hydrogen atoms, alkyl or substi tuted alkyl chains of no more than about carbons, or simple cyclic substituents as would be introduced into the cellulose by reacting it with aldehydes and dialdehydes such as formaldehyde, glyoxal, acetaldehyde, chloral, benazaldehyde, furfural, and the like. The preferred methylenating agent is formaldehyde since it can be effectively carried in aqueous solution, and since it will not cause an appreciable weight change in the fabric. In addition, the simple methylene crosslinks are highly stable and do not adversely interfere withfinishing adjuncts which may sometimes be employed in subsequent processing of the fabric.

The reactions of aldehyde with cellulose have a rather ancient origin and involve a long history of efforts to effectively control the reaction to a point where commercial processing of cellulosics with formaldehyde was feasible.

Theoretically, it is possible to react cellulose with a quantity of formaldehyde equal to about 17.2% of the weight of the cellulose. Introducing this quantity of formaldehyde into a cellulose fabric is a totally impractical procedure-the fabric will be completely destroyed. Many of the older fabric finishing processes utilizing formaldehyde as a stabilizing influence required the reaction of formaldehyde in quantities in excess of 2% 4 in order to obtain the desired results. However, in

order to get such quantities of formaldehyde permanently into the fabric required unduly harsh curing conditions which degraded the cellulose to a point where the resultant fabric was exceptionally tender. Probably the most objectionable feature of the methylenation processes heretofore proposed was the fact that the reaction Was very unpredictable and exceedingly difiicult to control to the extent necessary to enable continuous production of a uniform product and they were not used commercially. Therefore, with the advent of thermosetting resins as fabric stabilizing agents, the efforts to 7 use formaldehyde as a fabric finishing agent gradually known to the art.

decreased to a point where in recent years onlyacademic interest has been shown in this type of treatment.

I have discovered a commercially practical method for the methylenation of cellulose whereby it is possible to reproducibly methylenate cellulosic fabrics to the degree necessary to effect decrystallization and enhance the wet resilience without objectionably tendering the fabric provided certain special processing techniques are followed. Of particular importance is the necessity of providing the type of acid environment which will enable the reaction to proceed within time'limits that permit continuous commercial processing, which will not objectionably degrade the cellulose and which permit uniform products to be obtained. 7

The technique employed to obtain the desired enhancement of wet resilience and resin receptivity by the use of methylene crosslinks to modify the molecule chains which form the crystallites, can be briefly described as involving the following operational steps; applying the methylenating agent to the fabric and reacting the methylenating agent with the fabric under special conditions of acidity provided by a catalyst.

For purposes of this invention various aldehydes and dialdehydes can be employed as methylenating agents. The preferred agents are those which are small enough to enable them to penetrate into the crystallite phase. The aldehydes and dialdehydes '(either straight chain or cyclic) and which contain up to 6 carbons in general have the characteristic of being able to penetrate the crystallite phase and are reactable with cellulose to form methylene and substituted methylene crosslinks.

As previously described, in order to obtain the benefits and advantages according to this invention, an average of one methylene crosslink is to be formed for every 10 to 200 glucose residues. Therefore, it is necessary to apply the methylenating agent to the fabric in sufficient quantities which will insure obtaining the minimum of crosslinking.

With formaldehyde, a preferred methylenating agent, the desired degree of crosslinking can be obtained by applying the formaldehyde in quantities which, before curing, deposit from /2% to 5% formaldehyde (based on fabric weight) in the fabric.

The formaldehyde can be applied in Various ways I prefer to apply it by impregnating the fabric with aqueous solutions which contain formaldehyde. The impregnating bath can also contain other substances such as the catalyst, tinting agents, wetting agents, softeners, buffers, etc. which are compatible with one another.

Buifers which are especially useful in connection with the methylenation of cellulose fabrics are those materials which can react with the formaldehyde or other aldehydes at low temperatures to form compounds or complexes which will release the aldehyde under the curing conditions employed to effect the methylenation. A preferred class of buffering compounds are the alcohols and similar organic hydroXy compounds. Of the alcohols I prefer to employ isopropyl alcohol. This preference is due to the fact that it is somewhat less volatile than the lower alcohols, therefore minimizing fire hazards, and because it can be driven off readily in the subsequent processing.

- ponent catalyst systemone component being an acid and the other component being an acid salt of the Lewis acid type.

Suitable acids for the purposes of this invention include organic and inorganic acids and acid anhydrides such as maleic, tartaric, hydrochloric, phosphoric, citric, itaconic, succinic, and the like. I prefer, however, to employ polybasic acids since catalyst combinations prepared therefrom develop the desired degree of acidity for efiicient methylenation control and will not objectionably degrade the fabric. I g

The preferred acid salts for use in the catalyst system of this invention are the metal salts of either organic or inorganic acids of the Lewis acid type (i.e. electron acceptors); and especially the polyvalent metal salts of such acids and the acid salts of monovalent metals with polybasic acids. Where white goods are being processed, I also prefer to employ those salts whoseaqueous solutions are substantially colorless. Examples of especially useful acid salts include'aluminum chloride, strontium nitrate, tin chloride, aluminum acetate, magnesium nitrate, zirconium oxychloride, zinc nitrate, sodium bisulfate, and the like. One or more of these salts can be used in combination with the preferred acids.

Catalyst systems which have been found to be especially effective in insuring that the desired degree of methylenation will be obtained without seriously degrading the cellulose are those which have the acidity characteristics below 200 P. which will not appreciably catalyze the methylenation reaction and which develop an acid methylenating environment at temperatures between 200 and 275 F. Catalysts having acidity characteristics approximating those obtained by the use of the catalyst system formed by the combination citric acid (2 pounds), strontium nitrate tetrahydrate (3 pounds) and magnesium nitrate hexahydrate (4 pounds) in an impregnating bath made up to 100 gals. withwater, (i.e. the total catalyst system is approximately 1% of the weight of the bath and is sometimes hereinafter referred to as the 2-3-4 catalyst), have been found to be especially useful. The ratios and the total catalyst concentration can be varied widely provided the resulting system has the desired acidity characteristics as aforesaid.

I prefer to apply the catalyst to the fabric in the same bath used to impregnate fabric with the methylenating agent as only a single operation is required. However, the catalyst and the methylenating agent can be applied in multistep operations and in any desired sequence, as is well known in the art.

When the methylenating agent is applied from an aqueous solution, it is preferred to dry the fabric before instituting the 'cure as this will insure greater uniformity of the end product. The drying can be carried out on conventional drying equipment. However when this step is employed, it is important that the fabric should not be permitted to drop below the point of the moisture regain under the humidity conditions then prevailing in the mill. If the fabric is overdried, reproducible results cannot be obtained.

The curing operation involves heating the fabric for times and temperatures which insure that the desired degree of methylenation is obtained but in no case should it be carried to a point where the cellulose is objectionably degraded. Using the catalyst having the acidity characteristics approximating the 2-3-4 catalyst, effective curing can be obtained by 5 minute cures at 235 F. on

'6 light fabrics (4.00 yds./lb-. or lighter) 5 minute cures at 250 F. on conventional weight fabrics (between 3 and 4 lbs/yd.) and 5 minute cures at 275 F. on very heavy fabrics (i.e. those running 2.00-3.00 yds./lb.- or heavier).

While it is possible to effect methylenation with shorter cures at higher temperatures, I do not recommend operating in this Way unless the acidity characteristics of the catalyst are adjusted to provide for a milder curing environment. This'is necessary to avoid tendering the" fabric.

After curing the fabric can be Washed and dried to insure removal of the unreacted irnpregnants.

Fabric which has been treated in this way will be found to have good wash and wear properties and still possess satisfactory strength characteristics to permit machine laundering and drying, and the resin receptivity will be strikingly enhanced.

The wet resilience can be further enhanced by also treating the fabric with strong caustic soda solutions which are also capable of exerting a decrystallizing effect on the PHYSICO-CHEMICAL DECRYSTALLIZATIQN The technique employed to obtain the desired enhancement. of resin receptivity and wet resilience can be described generally as a modified mercerizing treatment-in which the casutic soda solutions are considerably stronger than those conventionally used in the mercerization of cotton. v

In conventional mercerization, caustic soda solutions of from 32 to 45 Tw are generally used. I cannot ob tain the desired effect by using caustic solutions of less than about 45 TW and best results are obtained with caustic solutions stronger than 60 TW. When the weaker strength conventional mercerizing solutions are used, the swelling is also accompanied by an appreciable deconvolution of the fiber hairs and this in turn exerts an undesirable infiuence on the hand. With the stronger caustic solutions Which I specify, swelling precedes the deconvolution or untwisting of the fiber hairs. Hence, by arresting the swelling at a point before deconvolution occurs (within about 10-60 seconds) I can convert a portion of the crystallitesto an amorphous condition without drastically modifying the hand. The arresting is effected by Washing the alkali out of the fabric with Water and dilute acidic solutions. Preferably Washing should commence within about 20-30 seconds after impregnation and the alkali should be substantially completely removed within about 60 seconds.

As in conventional mercerization the treatment can be carried out with or" without tension. However, more 1111iformlyconstant results are obtained when the fabric is under tension both lengthwise the Web and across the filling.

The treatment with the strong caustic solutions produces fabrics having good Wash and wear properties and greater Wet resilience than is obtained by conventional mercerization. The fabric has a pleasing full bodied hand and Examples The following examples will serve to illustrate how the invention may be carried out. i

EXAMPLE 1 A white cotton bleached (80 x 80 running 3.50 yds./lb.) which had not been previously mercerized was impregnated and squeezed at 60% pick-up in the follow- Triton X-100 (wetting agent, iso octyl phenyl polyethoxyethanol) u Water to make 100 gal.

The impregnated fabric was frame dried to the desired width. The drying was carried out to a point where the moisture content of the fabric was not permitted to fall below the moisture regain percentage under the prevailing humidity conditions.

The dried fabric was cured for minutw at 250 F. The cured fabric was then washed and dried.

The fabric produced in Example 1 was passed through a caustic mangle containing 66 Tw caustic soda solution at room temperature and passed onto a frame moving at 60 yards per minute, water Washing to remove the caustic soda was commenced within about -17 seconds after the fabric had left the mangle. The fabric was sour washed with A2 to 1% H 80 chemic washed (0.25% available C1 and dried to the desired width. The fabric was substantially completely neutralized within about 1 minute after leaving the mangle.

EXAMPLE 3 Example 2 was repeated using the same untreated fabric as was used in Example 1.

EXAMPLE 4 The fabric processed in Example 3 was treated as in Example 1.

In Example 1, 0.56% formaldehyde (giving a total dry add on of approximately 0.2% as compared with weight of the untreated fabric) was reacted with the cellulose. This prepresents an average of one methylene crosslink for every 33 glucose residues. The methylenation was determined according to the method of Kress (page 33, American Dyestuff Reporter, February 23, 1959). The wet and dry strength losses were well within acceptable commercial tolerances for this type of fabric and were approximately less than those obtained by resination of the same fabric to the degree necessary to obtain a comparable level of wash and wear properties. The treatment provides a fabric having a pleasing hand and the wash and wear properties were good. The resilience and stabilization were comparable to those obtained by resination.

In Example 2, the wash and Wear properties and the strength values were still further enhanced over those obtained in Example 1. The resultant fabric had a pleasing full bodied hand.

In Example 3, the treatment imparted some Wash and Wear properties, a full hand and the strength losses (wet and dry) were approximately 50% less than those obtained-by resination of the same fabric to the degree necessary to obtain comparable wash and wear properties.

The fabric produced according to Example 4 was very similar in hand to that obtained in Example 2 but with a slightly lower strength. The resilience, stabilization and wash and wear properties were increased over those ob-' tained in Example 2;

The durability of the effects produced in Examples 1-4 were in all instances superior to'those obtained in conventional resination. Even as much as 100 launderings will not destroy the effect.

' EXAMPLE 5 A dyed cotton x 80 running 3.50 yds./lb.) which had not been previously mercerized was impregnatedand squeezed at 60% pick-up in the following formulation:

Water to make gal.

The fabric was treated as in Example 1 except that the cure was for 2 minutes at 275 F.

In Example 5, 0.095% formaldehyde (giving a total dry add on of 0.05% as compared with the weight of the untreated fabric) was reacted with the cellulose. This represents an average of one methylene vcrosslink for every 195 glucose residues.

The wet and dry strength losses were approximately 35% less than those obtained by resination of the same fabric to the degree necessaryto obtain a comparable level of wash and wear properties. The durability was good but the resilience was slightly reduced from that obtained in Example 1. The finished fabric had a pleasing supple hand.

EXAMPLE 6- The fabric treated as in Example 1 was impregnated and squeezed at 65% pick-up with the following formula tion:

Lbs. Dimethylol triazone precondensate, 50% solids Zinc nitrate hexahydrate 15 A durable softener of the catonic type (Ahcovel 'X-57) -2 2O Acetic acid IV: A wetting agent (Triton X-100) 2 Water to make 100 gal.

The fabric was dried and cured at 300 F. for 3 minutes and thereafter washed and dried.

EXA'MPLE 7 The fabric treated as in Example 2 was further treated according to the process in Example 6.

EXA-MPLE 8 The fabric treated as in Example 3 was further treated as in Example 6;

EXAMPLE 9 Example 6 4.66 Example 7 4.71 Example 8 4.48 Example 9 3.85

Thus illustrating the greater resin afiinity of the fabrics treated according to the invention (Examples 6-8) as compared with the resin afiinity of a conventionally resinated fabric (Example 9).

The resiliency of the fabrics and wash and wear properties of the fabrics treated according to the invention were superior to the fabric having the conventional resination treatments, and despite the fact that more resin was fixed in the fabric in Examples 6-8 than in Example 9, the strength values of all fabrics were of approximately the same general order with fabrics treated according to the invention being equal to or superior to that of the conventionally treated goods.

Percent I claim:

1. The method of finishing partially methylenated natural cellulose fabrics containing an average of one methylene crosslink for every to 200 glucose residues which comprises contacting the fabric With strong caustic soda solutions of at least 45 T w for a time sufficient to cause decrystallization of cellulose crystallites, removing the caustic before appreciable fiber deconvolution occurs, impregnating the decrystallized cellulose with a textile finishing resin and thereafter fixing the resin in the fabric.

2. The method according to claim 1 wherein the resin is one which will not discolor and degrade the fabric on ironing after laundering in the presence of free halogen.

3. The method according to claim 2 wherein the resin is a dimethylol triazone precondensate.

4. The method according to claim 1 wherein before fixing the resin the fabric is subjected to a mechanical finishing operation. I

5. The method according to claim 4 wherein the mechanical finishing operation is carried out by passing the resin impregnated fabric through a calender.

6. The method according to claim 4 wherein the mechanical finishing operation is carried out by passing the resin impregnated fabric through a pleating machine.

7. The method according to claim 4 wherein the mechanical finishing operation is carried out by passing the resin impregnated fabric through a compressive shrinkage machine.

8. The product produced by the method of claim 1.

16 References Cited in the file of this patent UNITED STATES PATENTS 2,205,120 Heberlein June 1 8, 1940 2,412,832 Pfeifer Dec. 17, 1946. 2,436,076 -Pfeffer Feb. 17, 1948 2,512,195 Bener June 20, 1950 FOREIGN PATENTS 437,361 Great Britain Oct. 25, 1935 488,095 Great Britain June 29, 1938 727,888 Great Britain Apr. 13, 1955 727,890 Great Britain Apr. 13, 1955 OTHER REFERENCES Goldthwait: Textile Research Journal, January 1951, pp. 61.

Baer Abstract No. 597,153, Mar. 18, 1952, 656 O.G. 884.

Wood: Journal of the Society of Chem. Industry, Transactions and Communications, Nov. 6, 1931, pp. 411T to 413T.

Hall: Amer. Dyestuff Reporter, June 19, 1933, pp. 379- 381 and 399-401.

Textile Colorist, February 1941, p. 124.

Goldthwait: Amer. Dyestufi Reporter, Sept. 19, 1949, p. 678.

Edelstein: Amer. Dyestufr Reporter, July 26, 1937, pp. P423-P432.

Gailey: Journal of the Society of Dyers and Colourists, October 1951, pp. 358-359.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 139322 June 30 1964 Henry R. Hushebeck It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the grant (only) line I, for "Henry R0 Hushelbeck" read Henry R, Hushebeck Signed and sealed this 24th day of November 1964.,

(SEAL) Attest:

ERNEST W. SWIDER' EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. THE METHOD OF FINISHING PARTIALLY METHYLENATED NATURAL CELLULOSE FABRICS CONTAINING AN AVERAGE OF ONE METHYLENE CROSSLINK FOR EVERY 10 TO 200 GLUCOSE RESIDUES WHICH COMPRISES CONTACTING THE FABRIC WITH STRONG CAUSTIC SODA SOLUTIONS OF AT LEAST 45* TW FOR A TIME SUFFICIENT TO CAUSE DECRYSTALLIZATION OF CELLULOSE CRYSTALLITES, REMOVING THE CAUSTIC BEFORE APPRECIABLE FOR DECONVOLUTION OCCURS, IMPREGNATING THE DECRYSTALLIZED CELLULOSE WITH A TEXTILE FINISHING RESIN AND THEREAFTER FIXING THE RESIN IN THE FABRIC. 